Projector and control method for projector

ABSTRACT

A projector can be connected in cascade to another projector. Either a first mode for the projector to operate as a leading projector in the cascade connection or a second mode for the projector to operate as a second or subsequent projector in the cascade connection is set. The projector is made available for use on authentication by an authentication unit or on reception of use permission information of the projector by a receiving unit.

The entire disclosure of Japanese Patent Application No. 2011-148903filed Jul. 5, 2011 is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a projector and a control method for aprojector.

2. Related Art

According to a related art, as a method for preventing unauthorized useof a projector, inputting a personal identification number via a remotecontroller (remote) is known. However, in an installation environmentwhere plural projectors are used in the same place, it is troublesome toinput a personal identification number to all the projectors every timethe projectors are started up.

JP-A-2005-351996 discloses a projector which authenticates when a USBkey is inserted into or removed from the projector or when an RF tag isheld over the projector.

Such a projector can prevent unauthorized use of the projector withoutrequiring input of a personal identification number.

However, with the projector of JP-A-2005-351996, though input of apersonal identification number is not required, the user needs to carryout an operation for authentication near all the projectors and the timeand effort required before the use is not reduced. Moreover, when theprojector is hung from the ceiling, there is a problem that the usercannot carry out an operation of inserting or removing a USB key orholding an RF tag over the projector.

SUMMARY

An advantage of some aspects of the invention is to solve at least apart of the problems described above, and the invention can beimplemented as the following forms or application examples.

APPLICATION EXAMPLE

This application example of the invention is directed to a projectorwhich modulates and projects light emitted from a light source accordingto image information, including: a transmitting unit and a receivingunit which enable connection in cascade to at least one other projectorand are adapted for communicating with the other projector which isconnected in cascade; a mode setting unit which sets either a first modefor the projector to operate as a leading projector in the cascadeconnection or a second mode for the projector to operate as a second orsubsequent projector in the cascade connection; an input operation unitwhich accepts an input operation; an authentication unit whichauthenticates to make the projector available for use; and a controlunit which controls an operation of the projector. The control unitmakes the projector available for use on success of authentication bythe authentication unit or on reception of use permission information ofthe projector by the receiving unit.

According to this application example, the projector is made availablefor use on success of authentication by the authentication unit or onreception of use permission information. Thus, the time and effort toperform an authentication operation for all the plural projectors thatare connected in cascade can be eliminated.

Also, when the leading projector in the cascade connection isauthenticated, use permission information can be sequentially sent tothe second and subsequent projectors and these projectors becomeavailable for use. Thus, by authenticating only the leading oneprojector in the cascade connection, all the projectors can be madeavailable for use.

Also, first identification information which identifies the projectoritself and second identification information which identifies a nextprojector in the cascade connection may be provided. The secondidentification information together with the use permission informationmay be transmitted to the next projector. The next projector may becomeavailable for use when the second identification information receivedtogether with the use permission information coincides with the firstidentification information which identifies this next projector. Thus,when there is a projector that is connected in an unauthorized way inthe cascade connection, this projector can be prevented from becomingavailable for use.

Also, when the second or subsequent projector in the cascade connectiondoes not receive the use permission information within a predeterminedperiod of time, authentication may be carried out as with the leadingprojector in the cascade connection. Thus, even when a problem occurs ina connected projector for some reason and the use permission informationcannot be transmitted thereto, this projector can be made available foruse by authentication.

Moreover, the projector can be made available for use either on successof authentication by the authentication unit or on reception of the usepermission information. Thus, the time and effort to carry out theauthentication operation for all the plural projectors connected incascade can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a block diagram showing the circuit configuration of aprojector.

FIGS. 2A to 2D show a cascade connection of projectors. FIG. 2A shows astate where projectors are connected by wires. FIG. 2B shows a statewhere a projector PJ2 accepts use permission information from aprojector PJ1.

FIG. 2C shows a state where use permission information is transmittedfrom the projector PJ2 to a projector PJ3. FIG. 2D shows a state whereall the projectors are available for use.

FIG. 3 is a flowchart showing operations of a projector.

FIGS. 4A to 4C show examples of warning message. FIG. 4A shows anexample of warning message when authentication fails. FIG. 4B shows anexample of warning message when use permission information is notreceived within a predetermined period of time. FIG. 4C shows an exampleof warning message when received identification information does notconform.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the invention will be described withreference to the drawings. The following embodiment is not intended tolimit the invention described in the accompanying claims. Not allcombinations of features of the embodiment are essential to measures forresolution according to the invention.

First Embodiment

FIG. 1 is a block diagram showing the circuit configuration of aprojector 1 according to this embodiment.

As shown in FIG. 1, the projector 1 includes an image projection unit10, an OSD processing unit 16, an image signal processing unit 17, animage signal input unit 18, a control unit 20, a storage unit 21, aninput operation unit 23, a light source control unit 25, a power supplyterminal 30, a power supply unit 31, a receiving unit 41, a transmittingunit 42 and the like. These units are housed inside a casing of theprojector 1, not shown.

The image projection unit 10 includes alight source 11, three liquidcrystal light valves 12R, 12G, 12B as a light modulating device, aprojection lens 13 as a projection system, a liquid crystal driving unit14 and the like. The image projection unit 10 modulates, with the liquidcrystal light valves 12R, 12G, 12B, light emitted from the light source11, thus forms image light, and projects the image light from theprojection lens 13, thereby displaying an image on a screen SC or thelike.

The light source 11 includes a discharge-type light source lamp 11 amade up of an ultrahigh pressure mercury lamp, metal halide lamp or thelike, and a reflector 11 b which reflects light radiated by the lightsource lamp 11 a toward the liquid crystal light valves 12R, 12G, 12B.The light emitted from the light source 11 is converted to light with asubstantially uniform luminance distribution by an optical integrationsystem, not shown, and is separated into color light components of theprimary colors of light, red (R), green (G) and blue (B), by a colorseparation system, not shown. Then, the color light components becomeincident respectively on the liquid crystal light valves 12R, 12G, 12B.

Each of the liquid crystal light valves 12R, 12G, 12B includes a liquidcrystal panel formed by a pair of transparent substrates with liquidcrystal enclosed between these substrates. In the liquid crystal lightvalves 12R, 12G, 12B, plural pixels (not shown) arrayed in a matrix areformed and a drive voltage can be applied to the liquid crystal at eachpixel. As the liquid crystal driving unit 14 applies a drive voltagecorresponding to inputted image information to each pixel, each pixel isset to a light transmittance corresponding to the image information.

Therefore, the light emitted from the light source 11 is transmittedthrough and thus modulated by the liquid crystal light valves 12R, 12G,12B, and image light corresponding to image information is formed foreach color light component. The resulting image light components of theindividual colors are combined for each pixel by a light combiningsystem, not shown, and thus form color image light. Then, the colorimage light is projected in an enlarged manner onto the screen SC or thelike by the projection lens 13.

In the above embodiment, the projector 1 which projects light using thelight source lamp 11 a as the light source 11 is described as anexample. However, the invention can also be applied to a projector whichprojects light using an LED (light emitting diode) light source or laserlight source as the light source thereof. In the above embodiment, theimage projection unit 10 including the light source 11 and thetransmitting-type liquid crystal projection system using the threeliquid crystal light valves 12R, 12G, 12B as a light modulating deviceis described as an example. However, the image projection unit 10 mayalso employ light modulating devices of other display systems such asreflection-type liquid crystal display system or micro mirror devicesystem (light switch display system).

The control unit 20 includes a CPU (central processing unit), a RAM(random access memory) used for temporarily storing various data, andthe like. The control unit 20 operates according to a control program(not shown) stored in the storage unit 21 and thus performs generalcontrol over operations of the projector 1. That is, the control unit20, together with the storage unit 21, functions as a computer.

The control unit 20 includes an authentication unit 201 whichauthenticates the projector 1, a mode setting unit 202 which sets eithera first mode for the projector 1 to operate as a leading projector in acascade connection or a second mode for the projector 1 to operate as asecond or subsequent projector in the cascade connection, and a timer 20a which measures time.

The storage unit 21 includes a rewritable non-volatile memory such asflash memory or FeRAM (ferroelectric RAM). In the storage unit 21, acontrol program for controlling operations of the projector 1, varioussetting data prescribing operating conditions of the projector 1 and thelike are stored. In the storage unit 21, first identificationinformation 21 a which identifies the projector 1 and secondidentification information 21 b which identifies a projector of atransmission destination which is connected in cascade with theprojector 1 and to which information is transmitted by the transmittingunit 42 are saved as setting data.

When authentication succeeds with authentication information inputted bythe input operation unit 23, which will be described, the projector 1transmits use permission information P1 together with the secondidentification information 21 b from the transmitting unit 42 if thereis a projector that is registered in the second identificationinformation 21 b.

The input operation unit 23 is for the projector 1 to accept an inputoperation from a user. Although not shown, the input operation unit 23has plural operation keys for the user to give various instructions tothe projector 1. These operation keys are configured in the form of mainbody keys provided on an outer surface of the casing of the projector 1or in the form of a remote controller (remote) for carrying out inputoperations remotely.

The operation keys provided on the input operation unit 23 include apower key to switch power-on and power-off alternately, a input switchkey to switch plural input terminals for input to the image signal inputunit 18, a menu key to display setting menus for various settings in asuperimposed manner, a cursor key for the user to select a setting itemfrom a menu, a decision key, an escape key, and authentication operationkeys (for example, numeric keys) or the like to input authenticationinformation in order to make the projector 1 available for use.

As the user operates various operation keys on the input operation unit23, the input operation unit 23 outputs an operation signalcorresponding to the user's operation content to the control unit 20.The input operation unit 23 may be configured with a remote (not shown)capable of remote operations with a remote signal receiving unit (notshown). In this case, the remote issues an operation signal of infraredray or the like corresponding to the user's operation content. Theremote signal receiving unit receives this signal and transmits thesignal as control information to the control unit 20.

The image signal input unit 18 has plural image input terminals. At eachimage input terminal, image information is inputted from an externalimage output device such as video player device or personal computer viaa cable, not shown.

The image signal processing unit 17 converts the image informationinputted from the image signal input unit 18 to image informationrepresenting the gradation level of each pixel in the liquid crystallight valves 12R, 12G, 12B. Here, the converted image information isclassified by color components R, G, B and includes plural pixels valuescorresponding to all the pixels in each of the liquid crystal lightvalves 12R, 12G, 12B. A pixel value defines the light transmittance ofthe corresponding pixel. This pixel value prescribes the intensity(gradation level) of light that is transmitted through and emitted fromeach pixel.

The OSD processing unit 16 carries out processing to display an OSD(on-screen display) image such as menu image or message image in asuperimposed manner on a projection image, based on an instruction fromthe control unit 20. The OSD processing unit 16 has an OSD memory, notshown, and the OSD memory stores OSD image information representinggraphic patterns, fonts and the like for forming OSD images.

As the control unit 20 gives an instruction to display an OSD image in asuperimposed manner, the OSD processing unit 16 reads out necessary OSDimage information from the OSD memory and combines this OSD imageinformation with image information inputted from the image signalprocessing unit 17 so that the OSD image is superimposed at apredetermined position on the projection image. The image informationcombined with the OSD image information is outputted to the liquidcrystal driving unit 14.

Meanwhile, when no instruction to superimpose an OSD image is given bythe control unit 20, the OSD processing unit 16 outputs the imageinformation inputted from the image signal processing unit 17, directlyto the liquid crystal driving unit 14.

As the liquid crystal driving unit 14 drives the liquid crystal lightvalves 12R, 12G, 12B according to the image information inputted fromthe OSD processing unit 16, the liquid crystal light valves 12R, 12G,12B form an image corresponding to the image information and this imageis projected from the projection lens 13.

The light source control unit 25 controls the light source 11 to supplyor stop power, based on an instruction from the control unit 20, andthus switches the light source 11 on and off.

The power supply unit 31 is supplied with power of AC 100V or the likefrom outside via the power supply terminal 30. The power supply unit 31converts the inputted power (AC power) to predetermined DC power andsupplies power to each part of the projector 1. The power supply unit 31can also switch between a state where the power supply unit 31 suppliesnecessary power for projection of an image (operating power) to eachpart (power-on state) and a state where the power supply unit 31 stopssupply of operating power and stands by for an operation to turn onpower (standby state), based on an instruction from the control unit 20.

The receiving unit 41 communicates with the other projector(s) connectedin cascade and receives the use permission information P1 and the secondidentification 21 b.

The transmitting unit 42 communicates with the other projector(s)connected in cascade and transmits the use permission information P1 andthe second identification information 21 b.

Next, operations in a cascade connection of projectors according to thisembodiment will be described with reference to FIGS. 2A to 2D.

FIG. 2A shows a state where projectors PJ1, PJ2, PJ3 are connected bywire. The projectors PJ1, PJ2, PJ3 are connected in cascade, with atransmitting unit 42 a of the projector PJ1 connected to a receivingunit 41 b of the projector PJ2, and with a transmitting unit 42 b of theprojector PJ2 connected to a receiving unit 41 c of the projector PJ3.The projector PJ1 as the leading projector in the cascade connection isset to the first mode. The projectors PJ2, PJ3 as the second andsubsequent projectors are set to the second mode. At this point, all theprojectors PJ1, PJ2, PJ3 are on standby for use.

As shown in FIG. 2A, the projector PJ1 as the leading projector in thecascade connection carries out authentication on input of a personalidentification number from an input operation unit 23 a. When theauthentication is successful, the projector PJ1 becomes available foruse, as shown in FIG. 2B, and the use permission information P1 istransmitted from the projector PJ1 to the projector PJ2. At this point,also the second identification information 21 b is transmitted by thetransmitting unit 42 a. However, the description of this transmission isomitted here.

In FIG. 2B, as the projector PJ2 accepts the use permission informationP1 from the projector PJ1, the projector PJ2 becomes available for use,as shown in FIG. 2C, and the use permission information P1 istransmitted from the projector PJ2 to the projector PJ3.

In FIG. 2C, as the projector PJ3 accepts the use permission informationP1 from the projector PJ2, the projector P3 becomes available for use,as shown in FIG. 2D. Thus, all the projectors are now available for use.

Next, operations of the projector of this embodiment will be describedwith reference to the flowchart of FIG. 3.

As shown in FIG. 3, when the power of the projector 1 is turned on by apower-on operation on the input operation unit 23 (step S101), thecontrol unit 20 examines whether the first mode is set by the modesetting unit 202 (the projector 1 is the leading projector in thecascade connection) or not (step S102).

When the first mode is set by the mode setting unit 202 (step S102: Y),the processing shifts to step S103. When the first mode is not set bythe mode setting unit 202, that is, when the second mode is set (stepS102: N), the processing shifts to step S110.

In step S103, the authentication unit 201 authenticates based on inputof a personal identification number from the input operation unit 23 orthe like and processing shifts to step S104.

In step S104, the control unit 20 examines whether the authentication instep S103 is successful or not. When the authentication is successful(step S104: Y), the processing shifts to step S105. When theauthentication fails (step S104: N), the processing shifts to step S116.

In step S105, the control unit 20 examines whether effective informationis saved in the second identification information 21 b or not. Wheneffective information is saved in the second identification information21 b (step S105: Y), the processing shifts to step S106. When effectiveinformation is not saved in the second identification information 21 b(step S105: N), the processing shifts to step S107.

In step S106, the control unit 20 transmits the use permissioninformation P1 and the second identification information 21 b from thetransmitting unit 42 and shifts to step S107.

In step S107, the control unit 20 projects, by the image projection unit10, an image signal inputted from the image signal input unit 18 andends this flow.

In step S110, the control unit 20 starts measuring time by the timer 20a and shifts to step S111.

In step S111, the control unit 20 examines whether the elapsed time onthe timer 20 a is a predetermined time T1 (for example, 20 seconds) ornot. When the elapsed time on the timer 20 a is the time T1 (step S111:Y), a warning message M2 is projected for a predetermined period of time(step S112) and the processing shifts to step S103. An example of thewarning message M2 in this case is shown in FIG. 4B.

Meanwhile, when the elapsed time on the timer 20 a is not the time T1(step 111: N), the processing shifts to step S113.

In step S113, the control unit 20 examines whether the use permissioninformation P1 and the second identification information 21 b arereceived by the receiving unit 41 or not. When the use permissioninformation P1 and the second identification information 21 b arereceived (step S113: Y), the processing shifts to step S114. When theuse permission information P1 and the second identification information21 b are not received (step S113: N), the processing shifts to stepS111.

In the step S114, the control unit 20 examines whether the secondidentification information 21 b received in step S113 coincides with thefirst identification information 21 a or not. When the secondidentification information 21 b coincides with the first identificationinformation 21 a (step S114: Y), the processing shifts to step S105.When the second identification information 21 b does not coincide withthe first identification information 21 a (step S114: N), the processingshifts to step S115.

In step S115, the control unit 20 projects a warning message M3 for apredetermined period of time by the image projection unit 10 and shiftsto step S117. An example of the warning message M3 in this case is shownin FIG. 4C.

In step S116, the control unit 20 projects a warning message M1 for apredetermined period of time by the image projection unit 10 and shiftsto step S117. An example of the warning message M1 in this case is shownin FIG. 4A.

In step S117, the control unit 20 turns off the power of the projector 1to shift to a standby state and ends this operation flow.

As described above, according to the projector 1 of this embodiment, theprojector 1 is made available for use, on authentication by theauthentication unit or reception of the use permission information P1.Thus, the time and effort to authenticate all the plural projectorsconnected in cascade can be eliminated.

As the leading projector in the cascade connection is authenticated andbecomes available for use, the use permission information P1 issequentially sent to the second and subsequent projectors and theseprojectors become available for use. Thus, by authenticating only theleading projector 1 in the cascade connection, all the projectors can bemade available for use.

Also, the first identification information 21 a which identifies theprojector PJ1 and the second identification information 21 b whichidentifies the next projector PJ2 connected in cascade are provided. Thesecond identification information 21 b is sent together with the usepermission information P1 to the next projector PJ2.

When the second identification information 21 b received together withthe use permission information P1 coincides with the firstidentification information 21 a which identifies the next projector PJ2,the projector PJ2 becomes available for use.

Thus, when there is a projector 1 connected in an unauthorized manner inthe cascade connection, this projector 1 can be prevented from beingused.

Also, in the case where a projector operates as the second or subsequentprojector PJ2 in the cascade connection, when the use permissioninformation P1 is not received within a predetermined period of time,authentication is carried out by the authentication unit 201 similarlyto the leading projector PJ1 in the cascade connection. Thus, when theconnected projector PJ1 cannot transmit the use permission informationP1 for some reason, the next projector PJ2 connected in cascade can beauthenticated and the use permission information P1 can be transmittedthereto. Therefore, the authenticated projector PJ2 and the subsequentlyconnected projector (PJ3) can be made available for use.

The embodiment can be modified as follows.

Modification 1

In the projector 1 of the embodiment, when the first mode is set by themode setting unit 202, the authentication unit 201 carries outauthentication based on an input operation form the input operation unit23. However, authentication may be carried out using authenticationinformation acquired from an external storage medium. Thus, byconnecting a storage medium storing authentication information to oneprojector, all the projectors connected in cascade can be made availablefor use.

1. A projector which modulates and projects light emitted from a lightsource according to image information, the projector comprising: atransmitting unit and/or a receiving unit which enable connection incascade to at least one other projector and are adapted forcommunicating with the other projector which is connected in cascade; amode setting unit which sets either a first mode for the projector tooperate as a leading projector in the cascade connection or a secondmode for the projector to operate as a second or subsequent projector inthe cascade connection; an input operation unit which accepts an inputoperation; an authentication unit which authenticates to make theprojector available for use; and a control unit which controls anoperation of the projector; wherein the control unit makes the projectoravailable for use on success of authentication by the authenticationunit or on reception of use permission information of the projector bythe receiving unit.
 2. The projector according to claim 1, wherein thecontrol unit causes the authentication unit to perform authenticationwhen the first mode is set by the mode setting unit, the control unitcauses the receiving unit to accept the use permission information whenthe second mode is set by the mode setting unit, and when the projectorbecomes available for use, the control unit causes the transmitting unitto transmit the use permission information to the other projectorconnected in cascade.
 3. The projector according to claim 1, furthercomprising a storage unit that stores first identification informationwhich identifies the projector and second identification informationwhich identifies a destination projector to which the use permissioninformation is transmitted, wherein when the projector becomes availablefor use, the control unit causes the transmitting unit to transmit theuse permission information and the second identification information tothe other projector connected in cascade, and when the second mode isset by the mode setting unit, the control unit causes the receiving unitto receive the use permission information and the second identificationinformation, and when the second identification information coincideswith the first identification information, the projector is madeavailable for use.
 4. The projector according to claim 1, wherein whenthe second mode is set by the mode setting unit and use permissioninformation is not received by the receiving unit within a predeterminedperiod of time, the control unit causes the authentication unit toperform authentication.
 5. The projector according to claim 2, furthercomprising a storage unit that stores first identification informationwhich identifies the projector and second identification informationwhich identifies a destination projector to which the use permissioninformation is transmitted, wherein when the projector becomes availablefor use, the control unit causes the transmitting unit to transmit theuse permission information and the second identification information tothe other projector connected in cascade, and when the second mode isset by the mode setting unit, the control unit causes the receiving unitto receive the use permission information and the second identificationinformation, and when the second identification information coincideswith the first identification information, the projector is madeavailable for use.
 6. The projector according to claim 2, wherein whenthe second mode is set by the mode setting unit and use permissioninformation is not received by the receiving unit within a predeterminedperiod of time, the control unit causes the authentication unit toperform authentication.
 7. The projector according to claim 3, whereinwhen the second mode is set by the mode setting unit and use permissioninformation is not received by the receiving unit within a predeterminedperiod of time, the control unit causes the authentication unit toperform authentication.
 8. A control method for a projector whichmodulates and projects light emitted from a light source according toimage information, the projector including a transmitting unit and/or areceiving unit which enable connection in cascade to at least one otherprojector and are adapted for communicating with the other projectorwhich is connected in cascade, and a mode setting unit which sets eithera first mode for the projector to operate as a leading projector in thecascade connection or a second mode for the projector to operate as asecond or subsequent projector in the cascade connection, the methodcomprising: accepting an input operation; authenticating to make theprojector available for use; and making the projector available for useon success of the authentication or on the reception of use permissioninformation of the projector.